public class BinarySearch {
    public int takeAttendance(int[] records) {
        int n = records.length;
        int left = 0, right = n - 1;
        while (left < right) {
            int mid = left + (right - left) / 2;
            if (records[mid] == mid) {
                left = mid + 1;
            } else {
                right = mid;
            }
        }
        return left == records[left] ? left + 1 : left;
    }
}
